131–140 of 285 posts
Will be interesting to see the details when the report is actually public. It does sound like the scenario that Mentourpilot explored in the simulator is close to what happened, namely: Bad AoA probe causes MCAS to trim down, and also to indicate IAS disagree. Pilots increase throttle as per non-normal checklist to reduce the risk of stalling due to unreliable airspeed. Pilots disable electric stabilizer trim, as per…
A bad AoA probe wouldn't trigger IAS disagreement alert ( that is fed from the separate pitot tubes ) but could activate the corresponding stick-shaker which may make the pilots consider the possibility of IAS uncertainty. Just a minor quibble. Also increasing airspeed isn't a panacea for avoiding a stall, it is entirely possible to enter a high-speed stall if the AoA isn't managed. And in fact as mentioned speed can…
Additionally, pilots are reminded that an erroneous AoA can cause some or all of the following indications and effects:
- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Inability to engage autopilot.
- Automatic disengagement of autopilot - IAS DISAGREE alert.
- ALT DISAGREE alter.
- AOA DISAGREE alert (if the AOA indication option is installed)
- FEEL DIFF PRESS light
Will be interesting to see the details when the report is actually public. It does sound like the scenario that Mentourpilot explored in the simulator is close to what happened, namely: Bad AoA probe causes MCAS to trim down, and also to indicate IAS disagree. Pilots increase throttle as per non-normal checklist to reduce the risk of stalling due to unreliable airspeed. Pilots disable electric stabilizer trim, as per…
A bad AoA probe wouldn't trigger IAS disagreement alert ( that is fed from the separate pitot tubes ) but could activate the corresponding stick-shaker which may make the pilots consider the possibility of IAS uncertainty. Just a minor quibble. Also increasing airspeed isn't a panacea for avoiding a stall, it is entirely possible to enter a high-speed stall if the AoA isn't managed. And in fact as mentioned speed can…
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/...
Take a look at the graphs from the LionAir crash:
http://nrg.cs.ucl.ac.uk/mjh/lionair.png
You can see that both airspeed and altitude misread, in addition to AoA. If I understand correctly, the AoA is used by the ADIRU to correct misreading of the static pressure measured by the pitot-static tubes at high angles of attack. Thus one bad AoA probe can cause lots of symptoms simultaneously.
Earlier quoted context omitted.
No there isn't
But there is on the KC-46 tanker for the USAF, but unlike the MAX it cuts-out upon pilot control input: http://www.airforcemag.com/Features/Pages/2019/March%202019/... Again it derives from trying to push an older non-FBW design to new limits; a 767 wasn't designed for the large shifts in CoG which occur when offloading fuel in flight. A FBW type like the A330 that was its rival for the USAF contract can just subtly…
> The KC-46 has a two-sensor MCAS system, which “compares the two readings,” the Air Force said.
> Moreover, while the MAX 8 MCAS will reset and come back on automatically, the KC-46’s system is “disengaged if the pilot makes a stick input,” according to the Air Force
So it seems someone did their homework in this case (well hadn't they done, it would have gotten very ugly as well)
Earlier quoted context omitted.
Hard engineering problem - where do you open up the fuselage to get the people out? It's a tube so you can't weaken it. You also can't open a hole at the back and let them slide out backwards, you'd need a cylindrical tube in a tube which can then slide out. That's a HUGE amount of extra weight and complexity. Planes are so so much safer than cars. Before we parachute people out of passenger planes we should be eject…
Maybe just jettison wings+engines+cargo? Though I agree that broadly safety is solved. And obviously we must heavily reduce air travel to combat global warming.
Now what happens when this system malfunctions and one wing pops off for no reason in normal flight?
I’d love to see those people who accused the airline and crew of being incompetent to apologize in the light of these reports. It was shameful to see Boeing actively encouraging that narrative behind the scenes. Especially considering it plays on racist stereotypes equating „Africa“ with bad training/bad safety record/…. The idea of „dingy third world airline“ was ridiculous on its face, considering how bad a fit fly…
Totally agree. Some of the sentiments expressed here was borderline racist. (badly trained, overworked cluelless third world pilots not even capable to follow a checklist). One of the worst smear jobs was actually by the New York Times accusing the captain of the Ethiopian plane not having trained in a 787-MAX simulator. Hello? Wasn't that the whole sales pitch that the plane requires no training at all for certified…
He also claimed that the system had "artificial stupidity", that was the time when pilots first had the fun of encountering the many Airbus "flight laws".
Earlier quoted context omitted.
Either. Deeply seated racist beliefs are often honestly held, but that doesn't make them less shameful.
I think in this case it probably wasn't meant to be racism on Boeing's part--Boeing just has a history of immediately blaming the pilots for every crash. Latent racism may have helped some people believe it was the pilots' fault, but I wouldn't ascribe the actual racism part to Boeing in this case.
I am at least twice as likely to kill my airplane than my airplane is to kill me.
pilots should not have to fight the system. can there not be a simple button, "switch to manual"?
Airline safety has increased by a factor of 100 in the last 50 years, in terms of fatalities / miles travelled. Both in the past and now, far more accidents are the result of pilot error than failure of any system. Gloryfing the good old days of pilot jocks just isn’t supported by the actual data, this incident nonewithstanding.
the plane's crashing, and you're telling the pilots (who you think might be jocks which makes you feel...even less safe?), "No don't turn it off, I have 50 years of data that says systems are safe." perfect example of doing data wrong. crazy dangerous arrogant ideas like this contributed to this tragedy.
when the systems are failing, you better hope you have some pilot jocks / true fixed wing enthusiasts at the controls, who know how to make the systems work for them, or take control if they fail, rather than some data jocks, with blinkered faith in the systems, who count cost of lives as "notwithstanding".
flyers deserve competence from their systems and data, not just from their pilots. we need pilots who have earned their capabilities, and systems that have earned their impression of reliability. current MCAS occupies a privileged position in charge of safety it has not earned.
Earlier quoted context omitted.
It actually seems to be normal practice to quickly allocate blame, even when its quite clear that little if any investigation has actually taken place. One of the effects of allocating blame is that large swathes of the general public will "switch off" and not ask questions of their politicians, who in turn apply little pressure to improve or advocate for improved standards (which big business and comfortable institu…
>It actually seems to be normal practice to quickly allocate blame, even when its quite clear that little if any investigation has actually taken place. Readers would do well to remember this also applies to all the people who were 100% sure it was MCAS related before the wreckage even stopped smoldering.
Given the obvious similarities between the two incidents (same phase of flight, same apparent pitch control problems, known issue that would result in that behavior, etc), I don't think it was unreasonable for people to point out the likely connection.
